Electrical distribution.



No. 885,847. PATBNTED APR. 28, 1908.

L s; HIGHPIBLD. ELECTRICAL DISTRIBUTION.

APPLICATION FILED JAN. 20, 1908.

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JOHN SOMERVILLE HIGHFIELD, OF LONDON, ENGLAND.

ELECTRICAL DISTRIBUTION.

Specification of Letters Patent.

Patented April 28-, 1908a Application filed January 20, 1908. Serial No. 411,579.

T all whom it may concern:

Be it known that 1, JOHN SoMnnvILLE IIIenFrELn, M. Inst. C. E., M. Inst. E. E., electrical engineer, a subject of the King of Great Britain, residing at 16 Stratford Place, in the city and county of London, England, have invented new and useful improvements in Electrical Distribution, of which the following is a specification.

This invention relates particularly to high tension direct current series systems of electrical supply, and has for its object improvements in the method of distribution whereby greater security in the. supply is obtained, and a greater flexibility of arrangement to allow of the growth of the system.

The invention is applicable wherever the issuing and return lines of a system lie close together at points along their length, and consists in the provision of means whereby these two lines may be oined at intermediate points upon a breakdown. occurring in either of them, or when for other reasons it is desired to divide the system into parts.

The invention is illustrated. in the accompanying drawings, in which Figure 1 illustrates diagrammatically the general application of the invention, and Figs. 2 and 3 a special application which is of value on a rapidly developing system.

By way of example there are shown in Fig. 1 two generating stations a, b, which are connected in series by lines 0, d, which contain consuming devices or sub-stations e e 6 etc., t11(lf ,f ,f etc. Normally both the generating stations and the sub-stations are connected in series as shown. At each sub-station, or rather at all those near the middle of the system, there is provided a switch 9 joined by a lead. 7L to a point on the distributing line on the other side of one of the generating stations, and preferably close to another sub-station. This switch 9, which may obviously in practice be replaced by two separate switches, is capable of joining the lead 7L to either the incoming or outgoing line at the sub-stations. Voltmeters '0 p, c are provided at each station for connection between the line on either side of the station andearth, or between the end of the short circuiting line it and earth, and these serve to indicate the occurrence and position of a breakdown.

Suppose a fault should occur at 90, or suppose for any other reason it be desired to carry out alterations or other work on the line at that point, in the ordinary way this would necessitate an interruption of the supply, while the work was being done. WVith the present arrangement, however, by closing the switch 9 at station f to the righthand side of thestation and the switch at station e to the left-hand side of the station, the whole system may quite easily be divided into two, one of which, supplied by the central station. a, will comprise the consuming devices 6 6 f f whilethe other supplied fromstation b, will include consuming devices c 0 f 7. When this is done the supply can be continued as though nothing had happened, and there will simply be two separate systems, each with one generating station, instead. of a single system havin' two generating stations in series. It wil readily be seen that the position of the fault will be indicated by the voltmeter-s t at station f '0 at station f and c at station going to zero. These indications prove the fault to be between stations f? and f and it only remains to close the switches as above described in order to cut the fault out of circuit so that repairs can proceed. Clearly the system may be maintained in the same way should a fault occur, not in the middle of the system, but at another point say y. The only difference in this case is that station 6 will be more heavily loaded than station a, since this latter will only supply the consuming devices 6* and f Naturally it will be of no use to provide a switch 9 to join the conductors c to the left hand of station f because in that case generating station a would be short circuited. Precisely the same method of dealing with breakdown may be applied in cases where there are more than two generating stations. It is only necessary that the leads 7L and switches 9 should be so placed as not to short circuit any generating station if that can be avoided, because if one station. is thus thrown out of operation all the load has to be taken by those which are left. This method of splitting up one series system into two has a special application in the case of systems which are developing rapidly and in which the conductors at first form a complete loop. Such a system is illustrated by way of example in Fig. 2, where again a and b are generating stations, and c e 6 f 7, f are consuming devices joined in series with the generating stations. In any series system which begins in a small way the line loss is at first the most important feature. In order to diminish this the whole loop may be laid with two lines 7c, m in parallel so that the resistanceot the system is halved. Conductors are chosen of such a size that the current density for they initial maximum load is not more than half the maximum density at which the cables can be worked.

When by the addition of more and more consuming devices at points in the loop the system has grown suiliciently to demand the installation of more power at the generating stations, the system may conveniently be split into two in av manner analogous to that shown in Fig. 1. This may be effected in various ways. Perhaps the most obvious is that illustrated in Fig. 3. The pair of lines It, m are joined together on one side of each generating station. The system is thus split in two, and the connections to the machines within the station are changed so that the lines 7t and m are in series instead of in parallel. The generating station (1/ then supplies the consuming devices c 6*, etc, and the station I) the consuming devices f etc. Naturally the division of the system may be made in various other ways. It may be convenient to divide the system in the middle of each generating station, so that hall the machinery at each station is in the one system and the remaining half in the other system. Obviously the same principle may be extended to cases in which there are more than two generating stations, provided the lines 1. In a series system of direct-current electric supply the combination with central and f sub-stations and supply and consuming devices at said stations, oi main conductors joining said devices, intermediate conductors joined at one end to said main conductors, and means for connecting them to said main conductors at another point so as to complete a circuit through a part only of the supply and consuming devices.

2. In a series system of direct-current electric supply the combination with central and sub-stations and supply and consuming devices at said stations, oi" main conductors joining said devices, intermediate conductors joined at one end to said main conductors, means for connecting them to said main conductors at another point so as to com )lete a circuit through a part only of the supp y and consuming devices and means for indicating the occurrence and position oi an earth on the main conductors.

3. In a series system of direct-current electric supply, the combination with central and sub-stations, and supply and consuming devices at said stations, of a looped main conductor joining said devices in series, auxiliary conductors joined at one end to said main conductor, and terminating at the other in switching devices at sub-stations so situated on the main conductor that when said switching devices are closed loo )s are completed including some of said supply and consuming devices.

4. In a series system of direct-current elec tric supply the combination with a plurality of central stations and sub-stations, and supply and consuming devices at said stations, of a looped main conductor joining said devices in series, cross-connections between parts of said main conductor on opposite sides of a central station, switching means for completing said cross-connections, and voltmeters at sub-stations connected between the earth and said main conductor and cross-connections, whereby the occurrence and location of an earth on the main conductor may be indicated.

Signed at London, England this 9th day of January 1908.

JOHN SOlVIERA ILLE l'llbrlll ltllill.

In the presence of HUBERT A. GILL, ALBERT E. ODELL. 

